This invention relates generally to laser disc digital data video storage systems and particularly to a laser disc digital and video storage system that permits a plurality of users to independently and stimultaneously access a single laser disc and permits a user to access a plurality of discs.
The interactive video disc, or laser disc, which combines video images recorded on disc with random-access capability has become an important educational tool because it combines the potential of many teaching devices. Interactive video discs bring together the emotional power of television and the interactive power of the computer. The interactive video disc has had a major impact on education, training, information services, retail sales and entertainment. The interactive video disc makes possible a powerful educational experience in which computer based educational systems can display video imagery, real-time action, and stereo sound. Such learning systems allow interactive teaching, learner control of materials and minimal supervision. An interactive video disc can simulate reality, thereby providing an effective and inexpensive alternative to hands-on experience.
Currently, interactive video discs are used in industrial training, point of sale, retailing and entertainment. The key advantage of the interactive video disc systems is their ability to respond to the user. Programs stored in the video disc requires the viewer to play an active part in the presentation of materials. For example, if a student believes he knows a subject, he can take a test immediately instead of going through the lesson. Whenever the student answers the questions, the computer indicates whether the answers are correct and may direct the disc to go ahead or return to a previous lesson according to the student's score. Interactivity allows students greater freedom so that they may choose the order in which they study sections of a subject. By contrast, more traditional methods of training, such as live lectures, video tape and books are linear in that all the material is presented in the same order to every student. In watching video tape and listening to lectures, the student is a passive observer, which is a less effective learning role than if the student were an active participant.
In order to make the student more active, a programming technique known as branching creates alternative routes through a given set of materials. Branching lets student perceive at their own pace, see any materials they need or want to see, be tested on their comprehension of the materials and receive remedial work where needed.
Like the interactive video disc, micro computers are capable of branching, but presently they can not equal the sophistication of the video display which is made possible because the video disc stores more data than magnetic storage media ordinarily used in connection with microcomputers. More than 400,000 bits of information are required to create a single image on a television screen. A typical microcomputer disc holds up to 5 million bits, which is only enough information to store about 12 video images. At a standard video playback speed of 30 frames per second, an entire magnetic disc will hold only 0.4 seconds of real-time video. In addition, microcomputers construct screen displays too slowly to show real-time video. In contrast, a video disc can hold up to an hour of real-time video on each side. Furthermore, a video disc is less expensive than video tape.
A disadvantage of present interactive video disc systems is that each user requires a separate video disc and disc drive in addition to a video monitor. There are many situations where it would be advantageous to provide access to a single video disc by multiple users or multiple video discs by multi-users. For example, in an archive, such as a library card catalog, it would be advantageous to have the entire archive stored upon a single disc, or a single set of discs for large archives, and have the archive available for independent access by plural users. In a product promotion display at a trade show, for example, it would be advantageous to provide a single video disc and disc drive and plural video monitors from which prospective customers could independently view and interact with material contained upon the disc or multiple discs.